Alan Levi, who directed the episode Sleeper, has had a varied career. He was a director on The Fugitive TV series, JAG, Hercules: The Legendary Journeys, ER, Lois & Clark: The New Adventures of Superman, Dr. Quinn, Medicine Woman, Columbo, Quantum Leap, Miami Vice, Fame and The Invisible Man.

British comedy team Monty Python have been referenced a few times in Buffy: In Life Serial, Andrew and Warren mimic Monty Python’s parrot sketch when watching Buffy’s adventures with the Mummy hand (Warren: “This mummy hand has ceased to be!” Andrew: “It is an ex-mummy hand!”).
In the episode Primeval, …

Coldplay’s ‘Warning Sign’, from their album ‘A Rush of Blood’ is played in the episode Him, when Buffy takes R.J. into the empty classroom, and Dawn looks for him.

The following scene was cut from the episode Him:
Dawn: “And I’m even trying to understand that. A little. The rape part.”
Buffy: “He didn’t. I mean, he tried-”
Dawn: “Not that. I just… you guys had sex a lot, right? It’s not like you were strangers. Weren’t you even… being …

In Selfless, D’Hoffryn asks Aud if she used a Woodlow Transmogriphic spell to turn Olaf into a troll. She says she actually used Thornton’s Hope, with a touch of eelsbane.

In Selfless, Anyanka summoned a Grimslaw demon to kill a group of frat boys, in revenge for a cruel trick they had played on a female student. The demon is massive, speedy and spider-like, with a mouth in its abdomen. It uses the mouth to attack and rip out the …

The following scene was deleted from the episode Help:
Anya: “What a creepazoid. It’s like he didn’t just forget your birthday, but the day on which, in keeping with modern American tradition, one’s life is celebrated. One’s very self. He didn’t celebrate your self.”
But later…
Anya: “But anyway, this boyfriend of yours …

In Help, Willow admits to having written love poems about Xander and posted Doogie Howser fanfic on the internet when she was younger. Doogie Howser was a TV show starring Neil Patrick Harris about a teenage genius who is a doctor.

In Help, Cassie Newton is gifted with a second sight. She foresees several future events in that episode. She tells Buffy, “I know that you’ll go someplace dark underground”. She’s referring to Bring on the Night (where Buffy falls underground and first meets the Turok-Han) and Chosen (where Buffy goes …

Buffy is called ‘Buffy, the Vampire Slayer’ twice in the show. In Anne, she introduces herself to the demon as “I’m Buffy, the Vampire Slayer, and you are?” In Help, she goes to Cassie’s father’s house and says to Xander, “Buffy the Vampire Slayer would break down this door.”

The phone numbers shown in Buffy’s address book under the heading ‘Family Numbers’ in Same Time, Same Place are: Buffy’s work (555-0101), Xander’s office (555-0168), Dawn’s cell phone (555-0193). Giles’ number is on speed dial on the phone in the living room. 555 is the number commonly used for fictional …

The following line of Xander’s was deleted from the episode Beneath You:
“I forgot the high school’s unwritten rules of hallway etiquette. Of course, no one ever explained them to me. They’d just stuff me in a locker till I drew my own conclusion.”

In Beneath You, Buffy tells Principal Wood about the fate of Principal Flutie, who was eaten alive by a group of hyena-possessed students in The Pack.

The Sluggoth demon is a large worm-like creature with sharp teeth, seen in Beneath You. Spike says, “It’s a very large, very nasty, natural predator who died around the crusades.” The demon lives underground but comes out of the earth for food. It kind of looks like the penis-creature from …

We hear the German techno song ‘Von Der Tiefe’ by Stillste Stund in Beneath You, when the potential Slayer is murdered. The lyrics, “Von der Tiefe verschlingt es”, heard at the beginning of Beneath You, translates roughly to “from the depth it devours.”